#include<iostream>
using namespace std;
const int N = 510;
char s[N][N];
int n, m;
char temp[] = { 's','n','u','k','e' };
int st[N][N];
int dx[] = { -1,0,1,0 }, dy[] = { 0,1,0,-1 };
bool dfs(int x, int y, char c)
{
	//cout << "x==" << x << endl;
	//cout << "y==" << y << endl;
	//cout << "c==" << c << endl;
	st[x][y] = 1;
	if (x == n - 1 && y == m - 1)return 1;
	for (int i = 0; i < 4; i++) {
		int a = x + dx[i];
		int b = y + dy[i];
		if (st[a][b] || x < 0 || x >= n || y < 0 || y >= m)continue;
		int idx = 0;
		for (int j = 0; j < 5; j++) {
			if (temp[j] == c) {
				idx = j;
				break;
			}
		}
		idx = (idx + 1) % 5;
		if (s[a][b] == temp[idx]) {
			if (dfs(a, b, temp[idx])) {
				return 1;
			}
		}
	}
	return 0;
}
int main()
{
	cin >> n >> m;
	for (int i = 0; i < n; i++) {
		scanf("%s", s[i]);
	}
	if (s[0][0] != 's') {
		cout << "No" << endl;
		return 0;
	
	bool flag = 0;
	for (int i = 0; i < 5; i++) {
		if (s[n - 1][m - 1] == temp[i])flag = 1;
	}
	//cout << "flag==" << flag << endl;
	if (!flag) {
		cout << "No" << endl;
		return 0;
	}
	if (dfs(0, 0,'s'))cout << "Yes" << endl;
	else cout << "No" << endl;
	return 0;
}